将到skins.minecraft.net的请求导向本地, fix #7

src/main/java/org/to2mbn/authlibinjector/AuthlibInjector.java

@@ -3,14 +3,17 @@ package org.to2mbn.authlibinjector;
 import static java.nio.charset.StandardCharsets.UTF_8;
 import static java.util.Optional.empty;
 import static java.util.Optional.of;
-import static org.to2mbn.authlibinjector.util.IOUtils.readURL;
+import static org.to2mbn.authlibinjector.util.IOUtils.asString;
+import static org.to2mbn.authlibinjector.util.IOUtils.getURL;
 import static org.to2mbn.authlibinjector.util.IOUtils.removeNewLines;
 import java.io.IOException;
 import java.lang.instrument.ClassFileTransformer;
 import java.text.MessageFormat;
 import java.util.Base64;
 import java.util.Optional;
+import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.function.Consumer;
+import org.to2mbn.authlibinjector.httpd.DeprecatedApiHandle;
 import org.to2mbn.authlibinjector.transform.ClassTransformer;
 import org.to2mbn.authlibinjector.transform.SkinWhitelistTransformUnit;
 import org.to2mbn.authlibinjector.transform.YggdrasilApiTransformUnit;
@@ -26,7 +29,7 @@ public final class AuthlibInjector {
 
 	private AuthlibInjector() {}
 
-	private static boolean booted = false;
+	private static AtomicBoolean booted = new AtomicBoolean(false);
 	private static boolean debug = "true".equals(System.getProperty("org.to2mbn.authlibinjector.debug"));
 
 	public static void info(String message, Object... args) {
@@ -40,19 +43,17 @@ public final class AuthlibInjector {
 	}
 
 	public static void bootstrap(Consumer<ClassFileTransformer> transformerRegistry) {
-		if (booted) {
+		if (!booted.compareAndSet(false, true)) {
 			info("already booted, skipping");
 			return;
 		}
-		booted = true;
 
 		Optional<YggdrasilConfiguration> optionalConfig = configure();
-		if (!optionalConfig.isPresent()) {
+		if (optionalConfig.isPresent()) {
+			transformerRegistry.accept(createTransformer(optionalConfig.get()));
+		} else {
 			info("no config available");
-			return;
 		}
-
-		transformerRegistry.accept(createTransformer(optionalConfig.get()));
 	}
 
 	private static Optional<YggdrasilConfiguration> configure() {
@@ -66,7 +67,7 @@ public final class AuthlibInjector {
 		if (prefetched == null) {
 			info("fetching metadata");
 			try {
-				metadataResponse = readURL(apiRoot);
+				metadataResponse = asString(getURL(apiRoot));
 			} catch (IOException e) {
 				info("unable to fetch metadata: {0}", e);
 				return empty();
@@ -106,8 +107,14 @@ public final class AuthlibInjector {
 		for (String ignore : nonTransformablePackages)
 			transformer.ignores.add(ignore);
 
+		if (!"true".equals(System.getProperty("org.to2mbn.authlibinjector.httpd.disable"))) {
+			transformer.units.add(DeprecatedApiHandle.createTransformUnit(config));
+		}
+
 		transformer.units.add(new YggdrasilApiTransformUnit(config.getApiRoot()));
+
 		transformer.units.add(new SkinWhitelistTransformUnit(config.getSkinDomains().toArray(new String[0])));
+
 		config.getDecodedPublickey().ifPresent(
 				key -> transformer.units.add(new YggdrasilKeyTransformUnit(key.getEncoded())));
 

src/main/java/org/to2mbn/authlibinjector/httpd/DeprecatedApiHandle.java

@@ -0,0 +1,54 @@
+package org.to2mbn.authlibinjector.httpd;
+
+import static org.to2mbn.authlibinjector.AuthlibInjector.info;
+import java.io.IOException;
+import org.to2mbn.authlibinjector.YggdrasilConfiguration;
+import org.to2mbn.authlibinjector.transform.DeprecatedApiTransformUnit;
+import org.to2mbn.authlibinjector.transform.TransformUnit;
+
+public class DeprecatedApiHandle {
+
+	public static TransformUnit createTransformUnit(YggdrasilConfiguration configuration) {
+		DeprecatedApiHandle handle = new DeprecatedApiHandle(configuration);
+		return new DeprecatedApiTransformUnit(() -> {
+			handle.ensureStarted();
+			return "http://127.0.0.1:" + handle.getLocalApiPort();
+		});
+	}
+
+	private boolean started = false;
+	private YggdrasilConfiguration configuration;
+	private DeprecatedApiHttpd httpd;
+
+	private final Object _lock = new Object();
+
+	public DeprecatedApiHandle(YggdrasilConfiguration configuration) {
+		this.configuration = configuration;
+	}
+
+	public void ensureStarted() {
+		if (started)
+			return;
+		synchronized (_lock) {
+			if (started)
+				return;
+			if (configuration == null)
+				throw new IllegalStateException("configuration hasn't been set yet");
+			httpd = new DeprecatedApiHttpd(0, configuration);
+			try {
+				httpd.start();
+			} catch (IOException e) {
+				throw new IllegalStateException("httpd failed to start");
+			}
+			info("httpd is running on port {0,number,#}", getLocalApiPort());
+			started = true;
+		}
+	}
+
+	public int getLocalApiPort() {
+		if (httpd == null)
+			return -1;
+		return httpd.getListeningPort();
+	}
+
+}

src/main/java/org/to2mbn/authlibinjector/httpd/DeprecatedApiHttpd.java

@@ -0,0 +1,134 @@
+package org.to2mbn.authlibinjector.httpd;
+
+import static java.nio.charset.StandardCharsets.UTF_8;
+import static java.util.Optional.empty;
+import static java.util.Optional.of;
+import static org.to2mbn.authlibinjector.AuthlibInjector.debug;
+import static org.to2mbn.authlibinjector.AuthlibInjector.info;
+import static org.to2mbn.authlibinjector.util.IOUtils.asString;
+import static org.to2mbn.authlibinjector.util.IOUtils.getURL;
+import static org.to2mbn.authlibinjector.util.IOUtils.postURL;
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.io.UncheckedIOException;
+import java.util.Base64;
+import java.util.Optional;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+import org.to2mbn.authlibinjector.YggdrasilConfiguration;
+import org.to2mbn.authlibinjector.internal.org.json.JSONArray;
+import org.to2mbn.authlibinjector.internal.org.json.JSONException;
+import org.to2mbn.authlibinjector.internal.org.json.JSONObject;
+import fi.iki.elonen.NanoHTTPD;
+import fi.iki.elonen.NanoHTTPD.Response.Status;
+
+public class DeprecatedApiHttpd extends NanoHTTPD {
+
+	public static final String CONTENT_TYPE_JSON = "application/json; charset=utf-8";
+
+	// ^/MinecraftSkins/([^/]+)\.png$
+	private static final Pattern URL_SKINS = Pattern.compile("^/MinecraftSkins/(?<username>[^/]+)\\.png$");
+
+	private YggdrasilConfiguration configuration;
+
+	public DeprecatedApiHttpd(int port, YggdrasilConfiguration configuration) {
+		super("127.0.0.1", port);
+		this.configuration = configuration;
+	}
+
+	@Override
+	public Response serve(IHTTPSession session) {
+		return processAsSkin(session)
+				.orElseGet(() -> super.serve(session));
+	}
+
+	private Optional<Response> processAsSkin(IHTTPSession session) {
+		Matcher matcher = URL_SKINS.matcher(session.getUri());
+		if (!matcher.find()) return empty();
+		String username = matcher.group("username");
+
+		Optional<String> skinUrl;
+		try {
+			skinUrl = queryCharacterUUID(username)
+					.flatMap(uuid -> queryCharacterProperty(uuid, "textures"))
+					.map(encoded -> asString(Base64.getDecoder().decode(encoded)))
+					.flatMap(texturesPayload -> obtainTextureUrl(texturesPayload, "SKIN"));
+		} catch (UncheckedIOException | JSONException e) {
+			info("[httpd] unable to fetch skin for {0}: {1}", username, e);
+			return of(newFixedLengthResponse(Status.INTERNAL_ERROR, null, null));
+		}
+
+		if (skinUrl.isPresent()) {
+			String url = skinUrl.get();
+			debug("[httpd] retrieving skin for {0} from {1}", username, url);
+			byte[] data;
+			try {
+				data = getURL(url);
+			} catch (IOException e) {
+				info("[httpd] unable to retrieve skin from {0}: {1}", url, e);
+				return of(newFixedLengthResponse(Status.NOT_FOUND, null, null));
+			}
+			info("[httpd] retrieved skin for {0} from {1}, {2} bytes", username, url, data.length);
+			return of(newFixedLengthResponse(Status.OK, "image/png", new ByteArrayInputStream(data), data.length));
+
+		} else {
+			info("[httpd] no skin found for {0}", username);
+			return of(newFixedLengthResponse(Status.NOT_FOUND, null, null));
+		}
+	}
+
+	private Optional<String> queryCharacterUUID(String username) throws UncheckedIOException, JSONException {
+		String responseText;
+		try {
+			responseText = asString(postURL(
+					configuration.getApiRoot() + "api/profiles/minecraft",
+					CONTENT_TYPE_JSON,
+					new JSONArray(new String[] { username })
+							.toString().getBytes(UTF_8)));
+		} catch (IOException e) {
+			throw new UncheckedIOException(e);
+		}
+		debug("[httpd] query uuid of username {0}, response: {1}", username, responseText);
+		JSONArray response = new JSONArray(responseText);
+		if (response.length() == 0) {
+			return empty();
+		} else if (response.length() == 1) {
+			return of(response.getJSONObject(0).getString("id"));
+		} else {
+			throw new JSONException("Unexpected response length");
+		}
+	}
+
+	private Optional<String> queryCharacterProperty(String uuid, String property) throws UncheckedIOException, JSONException {
+		String responseText;
+		try {
+			responseText = asString(getURL(
+					configuration.getApiRoot() + "sessionserver/session/minecraft/profile/" + uuid));
+		} catch (IOException e) {
+			throw new UncheckedIOException(e);
+		}
+		if (responseText.isEmpty()) {
+			debug("[httpd] query profile of {0}, not found", uuid);
+			return empty();
+		}
+		debug("[httpd] query profile of {0}, response: {1}", uuid, responseText);
+		JSONObject response = new JSONObject(responseText);
+		for (Object element_ : response.getJSONArray("properties")) {
+			JSONObject element = (JSONObject) element_;
+			if (property.equals(element.getString("name"))) {
+				return of(element.getString("value"));
+			}
+		}
+		return empty();
+	}
+
+	private Optional<String> obtainTextureUrl(String texturesPayload, String textureType) throws JSONException {
+		JSONObject textures = new JSONObject(texturesPayload).getJSONObject("textures");
+		if (textures.has(textureType)) {
+			return of(textures.getJSONObject(textureType).getString("url"));
+		} else {
+			return empty();
+		}
+	}
+
+}

src/main/java/org/to2mbn/authlibinjector/transform/DeprecatedApiTransformUnit.java

@@ -0,0 +1,30 @@
+package org.to2mbn.authlibinjector.transform;
+
+import static java.util.Optional.empty;
+import static java.util.Optional.of;
+import java.util.function.Supplier;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+public class DeprecatedApiTransformUnit extends LdcTransformUnit {
+
+	// ^https?:\/\/(skins\.minecraft\.net)(?<path>\/.*)$
+	// => <localApiRoot>${path}
+	public static final Pattern REGEX = Pattern.compile("^https?:\\/\\/(skins\\.minecraft\\.net)(?<path>\\/.*)$");
+
+	public DeprecatedApiTransformUnit(Supplier<String> localApiRoot) {
+		super(string -> {
+			Matcher matcher = REGEX.matcher(string);
+			if (matcher.find()) {
+				return of(matcher.replaceAll(localApiRoot.get() + "${path}"));
+			} else {
+				return empty();
+			}
+		});
+	}
+
+	@Override
+	public String toString() {
+		return "deprecated-api-transform";
+	}
+}

src/main/java/org/to2mbn/authlibinjector/util/IOUtils.java

@@ -1,30 +1,52 @@
 package org.to2mbn.authlibinjector.util;
 
 import static java.nio.charset.StandardCharsets.UTF_8;
-import java.io.CharArrayWriter;
+import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
-import java.io.InputStreamReader;
+import java.io.OutputStream;
-import java.io.Reader;
+import java.net.HttpURLConnection;
 import java.net.URL;
 
 public final class IOUtils {
 
-	public static String readURL(String url) throws IOException {
+	public static byte[] getURL(String url) throws IOException {
 		try (InputStream in = new URL(url).openStream()) {
-			return asString(in);
+			return asBytes(in);
 		}
 	}
 
-	public static String asString(InputStream in) throws IOException {
+	public static byte[] postURL(String url, String contentType, byte[] payload) throws IOException {
-		CharArrayWriter w = new CharArrayWriter();
+		HttpURLConnection conn = (HttpURLConnection) new URL(url).openConnection();
-		Reader reader = new InputStreamReader(in, UTF_8);
+		conn.setRequestMethod("POST");
-		char[] buf = new char[4096]; // 8192 bytes
+		conn.setRequestProperty("Content-Type", contentType);
-		int read;
+		conn.setRequestProperty("Content-Length", String.valueOf(payload.length));
-		while ((read = reader.read(buf)) != -1) {
+		conn.setDoOutput(true);
-			w.write(buf, 0, read);
+		try {
+			conn.connect();
+			try (OutputStream out = conn.getOutputStream()) {
+				out.write(payload);
+			}
+			try (InputStream in = conn.getInputStream()) {
+				return asBytes(in);
+			}
+		} finally {
+			conn.disconnect();
 		}
-		return new String(w.toCharArray());
+	}
+
+	public static byte[] asBytes(InputStream in) throws IOException {
+		ByteArrayOutputStream out = new ByteArrayOutputStream();
+		byte[] buf = new byte[8192];
+		int read;
+		while ((read = in.read(buf)) != -1) {
+			out.write(buf, 0, read);
+		}
+		return out.toByteArray();
+	}
+
+	public static String asString(byte[] bytes) {
+		return new String(bytes, UTF_8);
 	}
 
 	public static String removeNewLines(String input) {